Insulative wall structures are disclosed for instance in U.S. Pat. No. 4,038,798 which issued Aug. 2, 1977 to Melvin H. Sachs and is titled "Composite Permanent Block-Form For Reinforced Concrete Construction and Method of Making Same". This patent discloses foam filled construction blocks having cardboard-tube-lined vertical passageways. The blocks are integrated into a wall construction by laying a plurality thereof in end-to-end and tiered relation and filling aligned vertical passageways with concrete which may be reinforced by reinforcing bars 64, FIG. 5. As compared to the Sachs construction, the present invention provides such improvements as: means for centrally supporting a reinforcing rod in a long vertical passageway while a concrete slurry is introduced thereinto and until it sets into a concrete column; and a high flexural strength casing which may be disposed at least at the central elevation portion of the passageway. Thus, the present invention comprises means for providing high slenderness ratio concrete columns having high compressive strength, and means for providing an enhanced level of flexural strength relative to the compressive strength of the columns for particular applications rather than providing excessive compressive strength to achieve a satisfactory level of side load strength in wall constructions comprising such columns.
U.S. Pat. No. 3,566,568 which issued Mar. 2, 1971 to Joseph Slobodian also discloses cellular blocks having vertical passageways in which reinforced concrete columns are formed in situ. This patent shows reinforcing rod retaining plate 23, FIGS. 1 and 4, for positioning the top end of a reinforcing rod 25 in each passageway but no means for centrally positioning or supporting the rod 25 in the passageway along its length while a concrete slurry sets up in the passageway.
U.S. Pat. No. 3,562,985 which issued Feb. 16, 1971 to J. A. Nicosia discloses yet another foam filled wall construction having vertically extending passageways therethrough. Nicosia does not, however, provide reinforced concrete columns to strengthen his construction as provided by the present invention.
While the prior art patents discussed above disclose some of the features of the present invention as described and shown herein, it is believed they fail both singly and collectively to teach, disclose, or suggest the present invention. They fail, for instance, to disclose such features of the present invention as spacing means for positively assuring that a reinforcing rod is supported and positioned axially in a high slenderness ratio concrete column, and means for significantly enhancing both the compressive strength and flexural strength of a wall comprising high slenderness ratio concrete columns without increasing the diameter of the columns; for instance, by encasing at least a central elevational portion of each column in a high flexural strength tubular casing.